# 7 INSPIRING CLASSROOM ACTIVITIES USING REALISTIC MATHEMATICS (Part 3)

7 INSPIRING CLASSROOM ACTIVITIES USING REALISTIC MATHEMATICS

(Part 3)

Composed by : Ratih Ayu Apsari

The content is summarized from seven articles of National Conference of Mathematics XIV (2008), Sriwijaya University.

[6] Puspita Sari : Empty Number Line Model in The Addition and Subtraction Learning.

This study is conducted for second graders students, which purposed to help children develop a framework of number relations to construe flexible mental arithmetic strategies and to make students use to solving addition and subtraction problems up to 100 both in context and in a bare number format using mental arithmetic strategies.

The researcher use the empty number line—a number line which has no numbers or markers on it— as a model to represent students’ strategies during mental computation. She also claimed that a empty number line allows the students to track their errors, because each step in students’ thinking can be recorded.

The empty number line could be introduced through a string of beads which alternate in colour for every ten of it, to help the students doing measurement activities. The empty number line is emerged first as *model of situation* and then it develops as the *model for situation*.

In the Picture 7 below, the example of empty number line is showing.

Picture 7: The emergence of an empty number line (Picture Modified)

[7] Rooselyna Ekawati : ‘Lapis’ Cake Problem as The Contextual Situation in Learning Fraction.

One of some goal of this research was to help students understanding the equivalence fractions. To encourage students in learning, the researcher use the question about “Lapis Surabaya” which is familiar with the subject experiments.

Kirana is given a challenge by hher father to divide the cake fairly. Under the bread, there is usually a paper which has equal size to the cake. Based on the paper, can you help Kirana to complete her father’s task?

Picture 8: Lapis Surabaya

From this context, the teacher guide the students to folding strategy using paper strip folding model. The researcher note that paper string folding is very good model to develop students understanding in comparing fraction and doing some operation, such as addition and find the difference between fraction.

In the first activity, students use basic paper fold strategy to divide cake in equal size. However, this strategy will be quite difficult when the students want to divide the whole cake into odd pieces. As the bridging to accomplish the equality task, the teacher can introduce the use of rubber band in the dividing paper process.